Ive done the plug screen several times, and the chamber once. Its pretty strait forward and makes a big difference on how the heater runs day to day. I used a angle grinder to slot a 10mm (i think) deep socket that allows you to remove the glow plug. usually need a small pick or something sharp to get the old screen out, it will be gunked in there good. There is a little pin hole down in the plug chamber, make sure to get this cleaned out with a wire brush.

Combustion chamber is a bigger undertaking but still very DIY. Mine was nasty, chisel and wire brush with brake cleaner. access to a sand blaster would be ideal!! I think brake cleaner is pretty flammable so make sure its not coated on it when you put it back together. There is also a paper seal that must be replaced when you put the chamber back together. I get my parts from the isotherm truck service center in denver, or heatso.com. There is a espar service manual pdf out there that is way more detailed in how to take it apart, replacement parts, ect. I also run kerosine through mine periodically as a PM of sorts. The kerosine seems to burn hotter and takes down some of the diesel build up

exactly. I had some of the extra clear fuel line lying around. disconnect the diesel "in line" from fuel pump, and run line right out of the kerosine bottle. I let it crank on high for an hour or two.

I had mine gunk up and stop working on me a couple winters ago. middle of a ski week, was not ideal. with regular PM I haven't had any additional issues the past couple years. Running it on high, doors wide open, after a night on low/med also seems to help keep build up down. If you start seeing some white smoke on start up, thats a tell tale sign of extensive build up and the need for a cleaning.